I don't know the answer to this question for sure, Catherine, but I DO know that luna moths range all the way up into Canada, so surely it must be fairly common for eggs to go through a freeze? I don't see how they could live up there if they weren't real cold hardy. I know that the eggs of the big moths, like lunas, are tough enough that you can pick them up individually with your fingers without worrying about damaging them.
My guess is that they'll do just fine. It may take them even longer than usual to hatch, though - even in summer, it takes them over a week, at least here.

Sherry

Thanks Sherry.
I'll just keep my fingers crossed.